Network switches, such as Asynchronous Transfer Mode (ATM) network switches, are employed to route received network traffic received on one of a plurality of input ports to one or more of a plurality of output ports for delivery ultimately to an intended destination or destinations over a network communications link. Input ports of the network switch may support a number of unidirectional physical links over which network traffic is received and output ports of the switch may likewise support a plurality of unidirectional physical links over which network traffic is transmitted.
In an ATM network switch, the data streams comprise pluralities of ATM cells. Multiple cell streams involving different data sources and destinations may be multiplexed on any given link. The cell streams, referred to as connections, are differentiated by fields which are contained in the cell header.
Cell reception at a network switch is largely non-deterministic and bursty in nature. Thus, large numbers of cells may be received at a network switch which need to be quickly routed from the respective input port to the appropriate output port or ports of the switch. Moreover, cells may be received over the various links which are competing for the same switch bandwidth. The network switch must manage such network traffic such that traffic which needs access to greater switch bandwidth are afforded such bandwidth while not starving other traffic which also needs access to the switch bandwidth.
Additionally, different types of network traffic have different service needs. For some types of traffic, such as video and audio traffic, a minimum bandwidth within the network switch must be assured and minimum delays must be maintained to faithfully reproduce the signal at the destination. Other types of data traffic are not subject to the same requirements.
For the above reasons it would be desirable to have a network switch which efficiently allocates the available switch bandwidth while assuring that minimum bandwidth and delay requirements of connections are satisfied.